U.S. losing its lead in a vital branch of physics

WASHINGTON—The United States is losing its lead in high-energy physics, a field of science it's dominated since the 1930s.

Scientists say Europe is now in the vanguard of a worldwide search to discover the deepest secrets that Mother Nature hides in bits and pieces of atoms.

At least 15 years, probably more, will pass before American physicists lead the pack again.

Particle physics, as the field is called, lies at the heart of all modern science. Particle researchers explore the nature of space and time, matter and energy, the basic building blocks of the universe.

The U.S. hosts the world's most powerful atom-smasher, the Tevatron at the Fermi National Accelerator Laboratory in Batavia, Ill., but it's scheduled to shut down in 2010. Smaller accelerators in Stanford, Calif., and at Cornell University in Ithaca, N.Y, will turn out the lights in 2008. These older machines are being phased out so that the money can be used on more up-to-date projects.

After that, it will be 2025, perhaps 2030, before a machine that's able to rip apart subatomic particles with sufficient force and precision could be operating on American soil.

"Accelerator facilities are shutting down before new ones are opening," said Burton Richter, a Nobel Prize-winning physics professor at the Stanford Linear Accelerator Center.

"For the richest country in the world to cede leadership in one of the most fundamentally important fields of science has significant negative implications for all of U.S. science," said Neal Lane, a former White House science adviser and an ex-director of the National Science Foundation in Washington.

"A decade or more without a U.S. accelerator will mean an exodus of some of our very best physicists to Europe and the possibility that young U.S. scientists will not go into the field and perhaps not choose science as a career," said Lane, a physics professor at Rice University in Houston.

The center of gravity in particle physics is moving to Geneva, the site of the Large Hadron Collider, a particle-splitter that's seven times more powerful than Fermi's Tevatron.

The $3.8 billion Large Hadron Collider, which occupies a 17-mile underground ring filled with massive magnets, is in the final stages of construction. When it's finished next year, it will smash protons—the largest particles in the nucleus of an atom—into each other at almost the speed of light. The collisions will spatter a spray of quarks, photons and other particles into huge detectors that will analyze their patterns.

Among other things, scientists hope that the experiments will help them understand "dark matter" and "dark energy"—phenomena discovered in the last 10 years—which make up 95 percent of the universe, leaving only 5 percent for the ordinary atoms in stars, trees and people.

Thousands of the world's top scientists, including many Americans, are flocking to Geneva to take part in the Large Hadron Collider project. The U.S. is contributing $531 million to it, but Americans have only the status of observers—not official members—of the consortium.

In a 127-page report on the future of particle physics that was published last year, a committee of the National Academy of Sciences predicted that "the intellectual center of gravity of the field will move abroad."

Europe is investing twice as much as the United States in particle physics, and Japan nearly half as much, according to committee Chairman Harold Shapiro, a former president of Princeton University.

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"Within a few years, a majority of U.S. experimental particle physicists will be involved in experiments being conducted in other countries," the Shapiro committee declared.

To meet this challenge, U.S. scientists hope to land the proposed successor to the Large Hadron Collider, an even more efficient particle accelerator known as the International Linear Collider. Instead of protons, the International Linear Collider will crash electrons into their antimatter twins, positrons, to find new particles.

"For the U.S. to be a leader in high-energy particle physics, the ILC must be located in the U.S," Lane said. The cost—estimated at $10 billion to $15 billion—would be split among international partners, with the host country picking up the lion's share.

Raymond Orbach, the undersecretary for science at the U.S. Department of Energy, told disappointed high-energy physicists in February that the International Linear Collider won't be ready until at least 2025, and more likely the end of that decade.

"Schedules will almost certainly be lengthier than the optimistic projection," Orbach said. "It could take us well into the mid 2020s, if not later."

During that time, scientists based in Europe may start to unravel some profound mysteries, such as whether the universe has a number of hidden dimensions beyond the three familiar visible ones.

New accelerators such as the International Linear Collider might discover such higher dimensions by "kicking particles with enough energy that they could disappear into the extra dimensions," said Fred Gilman, head of the physics department at Carnegie Mellon University in Pittsburgh and chairman of the Department of Energy's High Energy Physics Advisory Committee. "Particle accelerators would allow the discovery of such dimensions, and measurement of their shapes and sizes."

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The Large Hadron Collider Web site is at http://lhc.web.cern.ch/lhc

The International Linear Collider Web site is at www.linearcollider.org/cms

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Particle physics is the branch of science that studies the elementary particles and forces inside atoms. The so-called "Standard Model" includes protons, neutrons, electrons, quarks, hadrons, bosons, neutrinos and a flock of other units that can be detected only at extremely high energies. Particle physics underlies other disciplines, such as nuclear physics (nuclear energy, atom bombs), astrophysics (stars, galaxies), solid-state physics (magnets, electronics, optics), and materials physics (metals, plastics, crystals).